COMPARISON OF SEDIMENTARY PATTERNS IN MARSH SYSTEMS OF DREDGED AND NATURAL ESTUARIES

Analysis of marsh cores taken from a tributary of a regularly dredged urban estuary and a nearby relatively undisturbed estuary reveal differences in sediment patterns and sources. Current paradigms predict that high marsh systems accrete mostly autochthonous organic matter. However, dredging of an estuary radically alters the hydrodynamics and sediment transport of the estuary, maintaining it in a constant state of disequilibrium. Organic Carbon content, C/N ratios, del C-13 values, stratigraphy and facies composition show the differences in sediment sources, bioturbation processes, and stratigraphic patterns between the dredged and natural systems. These results have implications for the use of artifical wetlands to ameliorate particle adherent contaminants such as PAH's and heavy metals.